The BLISS cluster randomised controlled trial of the effect of 'active dissemination of information' on standards of care for premature babies in England (BEADI) study protocol [ISRCTN89683698]

Table 4 Power calculation for changes in practice for various assumptions of % with practice pre-intervention – p₁(20–60%), p₂ (30–90%), assuming 80% power at 5% level of statistical significance (2-sided test), for sizes of effect ≤ 2 and for cluster size six (numbers of annual live births per hospital)

ICC assumption required for 780 babies
p ₁	P ₂
	30	35	40	45	50	55	60	65	70	75	80	85	90
60									0.02	0.31
55									0.28
50								0.26
45							0.25	0.6
40						0.25	0.6
35				0.01	0.26	0.6
30			0.02	0.28
25		0.04	0.31
20	0.06	0.36